Add tests for buffer corruption after PEM write
Zero remaining bytes in buffer after writing PEM data and add checks to
ensure that this is the case.
Signed-off-by: Paul Elliott <paul.elliott@arm.com>
diff --git a/library/pem.c b/library/pem.c
index 9eff10e..8c07048 100644
--- a/library/pem.c
+++ b/library/pem.c
@@ -510,6 +510,9 @@
*p++ = '\0';
*olen = p - buf;
+ /* Clean any remaining data previously written to the buffer */
+ memset( buf + *olen, 0, buf_len - *olen );
+
mbedtls_free( encode_buf );
return( 0 );
}
diff --git a/tests/suites/test_suite_pkwrite.function b/tests/suites/test_suite_pkwrite.function
index 71aa595..c6aa05a 100644
--- a/tests/suites/test_suite_pkwrite.function
+++ b/tests/suites/test_suite_pkwrite.function
@@ -17,7 +17,7 @@
unsigned char check_buf[5000];
int ret;
FILE *f;
- size_t ilen;
+ size_t ilen, pem_len, buf_index;
memset( buf, 0, sizeof( buf ) );
memset( check_buf, 0, sizeof( check_buf ) );
@@ -28,12 +28,20 @@
ret = mbedtls_pk_write_pubkey_pem( &key, buf, sizeof( buf ));
TEST_ASSERT( ret == 0 );
+ pem_len = strlen( (char *) buf );
+
+ // check that the rest of the buffer remains clear
+ for( buf_index = pem_len; buf_index < sizeof( buf ); ++buf_index )
+ {
+ TEST_ASSERT( buf[buf_index] == 0 );
+ }
+
f = fopen( key_file, "r" );
TEST_ASSERT( f != NULL );
ilen = fread( check_buf, 1, sizeof( check_buf ), f );
fclose( f );
- TEST_ASSERT( ilen == strlen( (char *) buf ) );
+ TEST_ASSERT( ilen == pem_len );
TEST_ASSERT( memcmp( (char *) buf, (char *) check_buf, ilen ) == 0 );
exit:
@@ -49,7 +57,7 @@
unsigned char check_buf[5000];
int ret;
FILE *f;
- size_t ilen;
+ size_t ilen, pem_len, buf_index;
memset( buf, 0, sizeof( buf ) );
memset( check_buf, 0, sizeof( check_buf ) );
@@ -60,12 +68,20 @@
ret = mbedtls_pk_write_key_pem( &key, buf, sizeof( buf ));
TEST_ASSERT( ret == 0 );
+ pem_len = strlen( (char *) buf );
+
+ // check that the rest of the buffer remains clear
+ for( buf_index = pem_len; buf_index < sizeof( buf ); ++buf_index )
+ {
+ TEST_ASSERT( buf[buf_index] == 0 );
+ }
+
f = fopen( key_file, "r" );
TEST_ASSERT( f != NULL );
ilen = fread( check_buf, 1, sizeof( check_buf ), f );
fclose( f );
- TEST_ASSERT( ilen == strlen( (char *) buf ) );
+ TEST_ASSERT( ilen == pem_len );
TEST_ASSERT( memcmp( (char *) buf, (char *) check_buf, ilen ) == 0 );
exit:
diff --git a/tests/suites/test_suite_x509write.function b/tests/suites/test_suite_x509write.function
index aba23d4..f522311 100644
--- a/tests/suites/test_suite_x509write.function
+++ b/tests/suites/test_suite_x509write.function
@@ -44,7 +44,7 @@
unsigned char buf[4096];
unsigned char check_buf[4000];
int ret;
- size_t olen = 0, pem_len = 0;
+ size_t olen = 0, pem_len = 0, buf_index;
int der_len = -1;
FILE *f;
const char *subject_name = "C=NL,O=PolarSSL,CN=PolarSSL Server 1";
@@ -70,6 +70,11 @@
pem_len = strlen( (char *) buf );
+ for( buf_index = pem_len; buf_index < sizeof( buf ); ++buf_index )
+ {
+ TEST_ASSERT( buf[buf_index] == 0 );
+ }
+
f = fopen( cert_req_check_file, "r" );
TEST_ASSERT( f != NULL );
olen = fread( check_buf, 1, sizeof( check_buf ), f );
@@ -112,7 +117,7 @@
unsigned char check_buf[5000];
mbedtls_mpi serial;
int ret;
- size_t olen = 0, pem_len = 0;
+ size_t olen = 0, pem_len = 0, buf_index;
int der_len = -1;
FILE *f;
rnd_pseudo_info rnd_info;
@@ -181,6 +186,11 @@
pem_len = strlen( (char *) buf );
+ for( buf_index = pem_len; buf_index < sizeof( buf ); ++buf_index )
+ {
+ TEST_ASSERT( buf[buf_index] == 0 );
+ }
+
f = fopen( cert_check_file, "r" );
TEST_ASSERT( f != NULL );
olen = fread( check_buf, 1, sizeof( check_buf ), f );